... low pressure loss 4, Easy installation Electronic flow sensor (Thermal differential type)Principle Based on the ... differential resistances value is the basis of determining the flow velocity . Feature1,No movable parts . 2, ... 7,Compact structure . 8, LED indicator display flow trend and switch state . Technical data Set range ... ( water),3…300cm/s(oil),20…2000cm/s(air)Output: PNP, NPN, Relay ,4-20mA, ...